New profile: ssmtp (#5544)

* disable-programs.inc: add ssmtp support

* Create ssmtp.profile

* ssmtp: support Debian/Ubuntu

* README.md: add ssmtp to 'New profiles' section

* disable-common.inc: move ssmtp support to keep CI happy

* ssmtp: improve dead.letter comment

Suggested in [review](https://github.com/netblue30/firejail/pull/5544#pullrequestreview-1225322546).

README.md

@@ -336,7 +336,7 @@ Stats:
 ### New profiles:
 
 onionshare, onionshare-cli, opera-developer, songrec, gdu, makedeb, lbry-viewer, tuir,
-cinelerra-gg, tesseract, avidemux3_cli, avidemux3_jobs_qt5, avidemux3_qt5, 
+cinelerra-gg, tesseract, avidemux3_cli, avidemux3_jobs_qt5, avidemux3_qt5, ssmtp
 
 
 

etc/inc/disable-programs.inc

@@ -1181,6 +1181,7 @@ blacklist ${HOME}/yt-dlp.conf.txt
 blacklist ${RUNUSER}/*firefox*
 blacklist ${RUNUSER}/akonadi
 blacklist ${RUNUSER}/psd/*firefox*
+blacklist /etc/ssmtp
 blacklist /tmp/.wine-*
 blacklist /tmp/akonadi-*
 blacklist /var/games/nethack

etc/profile-m-z/ssmtp.profile

@@ -0,0 +1,75 @@
+# Firejail profile for ssmtp
+# Description: Extremely simple MTA to get mail off the system to a mailhub
+# This file is overwritten after every install/update
+quiet
+# Persistent local customizations
+include ssmtp.local
+# Persistent global definitions
+include globals.local
+
+blacklist ${RUNUSER}
+blacklist /usr/libexec
+
+noblacklist /etc/logcheck
+noblacklist /etc/ssmtp
+noblacklist /sbin
+noblacklist /usr/sbin
+
+noblacklist ${DOCUMENTS}
+include disable-common.inc
+include disable-devel.inc
+include disable-exec.inc
+include disable-interpreters.inc
+include disable-proc.inc
+include disable-programs.inc
+include disable-shell.inc
+include disable-xdg.inc
+include disable-X11.inc
+
+mkfile ${HOME}/dead.letter
+whitelist ${HOME}/dead.letter
+whitelist ${DOCUMENTS}
+whitelist ${DOWNLOADS}
+include whitelist-common.inc
+include whitelist-run-common.inc
+include whitelist-runuser-common.inc
+include whitelist-usr-share-common.inc
+include whitelist-var-common.inc
+
+apparmor
+caps.drop all
+ipc-namespace
+machine-id
+netfilter
+no3d
+nodvd
+#nogroups breaks app
+noinput
+nonewprivs
+noprinters
+#noroot breaks app
+nosound
+notv
+nou2f
+novideo
+protocol unix,inet,inet6
+seccomp
+seccomp.block-secondary
+tracelog
+
+disable-mnt
+# private works but then we lose ${HOME}/dead.letter
+# which is useful to get notified on mail issues
+#private
+private-bin mailq,newaliases,sendmail,ssmtp
+private-cache
+private-dev
+private-tmp
+
+dbus-user none
+dbus-system none
+
+memory-deny-write-execute
+restrict-namespaces
+read-only ${HOME}
+read-write ${HOME}/dead.letter